Rotary/linear convertor

ABSTRACT

A rotary/linear convertor which comprises a first member may be in the form of a piston (14, 15, 16, 17, 114, 115, 116, 117) and a guide which is preferably in the form of a cylinder (12, 112) the first member being arranged for linear movement within or along the guide and a second member (23, 24, 137) which is adapted for rotational movement. The convertor further includes connecting means operatively connecting the first and second members so that the respective linear or rotational movement of one member causes the respective linear or rotational movement of the other member. The connecting means comprises a connecting shaft (20, 120, 121, 122, 123) disposed eccentrically of the central axis of the first member, first coupling means (29, 29a, 28, 28a, 127, 131) operatively connecting the first member to the connecting shaft so that axial reciprocation of that first member causes orbital movement of the connecting shaft and vice versa and second coupling means (21, 22, 132, 133, 134, 135) operatively connecting the connecting shaft to the second member so that the orbital movement of the connecting shaft causes rotation of the second member and vice versa.

This invention relates to a device for converting linear motion torotary motion and vice-versa. For example, the principles of thisinvention may be applied to a fluid operated engine or motor andparticularly to such a device which is capable of producing rotarymotion of a shaft to power motor vehicles, farm machinery, andstationary devices such as pumps, heat exchangers, generators and so on.

In particular, the engine or motor of this preferred application iscapable of being operated by a wide range of fluids and in fact may beoperated with any type of expandable fluid, whether or not priorignition is required. Thus, the device may be operated with a compressedor pressurised fluid such as air, steam or helium which is allowed toexpand, or alternatively the motor may be operated with fluids such aspetrol, gas or other hydrocarbon or similar fuel which require ignitionto cause the necessary expansion. Conversely, when operated as a pump,the device of this invention may be used to pump or compress both liquidand gaseous fluids.

In Australian Patent Specification No. 501555, there is described afluid operated device comprising: a cylinder member, at least twomutually opposed piston members movable axially therein, a workingchamber within said cylinder member defined by opposing ends of saidpiston members and the inner wall of said cylinder member, said cylindermember being provided with inlet and outlet means communicating withsaid working chamber for admission of working fluid to said chamber andfor removal of spent working fluid from said chamber, respectively; ashaft member extending through said piston members and said cylindermember concentrically with said members; first coupling means couplingthe piston members to one of the other mentioned members such that axialreciprocation of the piston member causes rotation of the piston membersrelative to said one of the other mentioned members, second couplingmeans coupling the piston members to the other mentioned members toprevent relative rotation of the piston members and said other one ofthe other mentioned members while permitting axial reciprocation of thepiston members; and valve means in said working chamber operativelycoupled to said shaft member for rotation with said shaft memberrelative to the cylinder member to control movement of working fluidinto and out of said working chamber through said inlet and outletmeans. In particular embodiments disclosed therein, the first couplingmeans comprises at least one continuous sinusoidal guidway formed in asurface of either the piston member or the cylinder member, and at leastone associated cam follower mounted in a facing surface of the cylindermember or the piston member, respectively, to project therefrom andengage the guideway; and the second coupling means of these embodimentscomprises at least one axially extending guideway formed in a surface ofthe piston member or the shaft member, and at least one associated camfollower mounted in a facing surface of the shaft member or the pistonmember, respectively, to project therefrom and engage the guideway. Inalternative embodiments, the arrangement of the first and secondcoupling means is reversed in that the first coupling means comprises atleast one continuous sinusoidal guideway formed in a surface of thepiston member or the shaft member, and at least one associated camfollower mounted in a facing surface of the shaft member or the pistonmember, respectively, to project therefrom and engage the guideway; andthe second coupling means comprises at least one axially extendingguideway formed in a surface of the piston member or the cylindermember, and at least one associated cam follower mounted in a facingsurface of the cylinder member or the piston member, respectively, toproject therefrom and engage said guideway.

It is an object of the present invention to provide an improvedrotary/linear convertor which is relatively simple in construction andmore efficient. According to the present invention there is provided arotary/linear convertor comprising;

a first member and a guide, said first member having a central axis andbeing adapted for linear movement in the direction of said central axiswithin or along said guide;

a second member adapted for rotational movement;

connecting means operatively interconnecting said first and secondmembers so that respective linear or rotational movement of one saidmember causes respective linear or rotational movement of the other saidmember;

characterized in that said connecting means comprises;

a connecting shaft disposed eccentrically of said central axis of saidfirst member;

first coupling means operatively connecting said first member to saidconnecting shaft such that axial reciprocation of said first membercauses orbital movement of said connecting shaft and vice versa; and

second coupling means operatively connecting said connecting shaft tosaid second member so that said orbital movement of said connectingshaft causes rotation of said second member and vice versa.

Preferably the first coupling means comprises a sleeve operativelyconnected to the first member for axial reciprocation therewith thatsleeve being associated with the connecting shaft for axialreciprocation relative thereto and at least one link member extendingbetween the sleeve and a mounting which is in a fixed position. Theposition of the mixed mounting may be adjustable if desired.

Preferably the second coupling means comprising a disc-like membermounted for rotation about an axis, the connecting shaft beingeccentrically connected with respect to that axis to the disc-likemember, the second member being operatively connected to the disc-likemember.

In one form the first coupling means comprises a plurality of linkmembers extending between the sleeve and, respective mountings which arefixed. Preferably each link member is pivotally connected to said sleeveand to the mounting for limited universal movement.

In one arrangement the second member is operatively connected to thedisc-like member co-axially therewith. In another arrangement the secondmember is radially displaced from the axis of the disc-like member andoperatively connected thereto by transmission means. Preferably thedisc-like member comprises a circumferential gear section adapted toengage a further gear which is operatively connected to the secondmember.

Preferably the first member comprises a piston and the guide comprises acylinder having a working chamber therein. Inlet means and outlet meansare provided for communicating with the working chamber for theadmission and removal of the working fluid therefrom. In one preferredform the first member comprises two pistons disposed within the cylinderthere being a single working chamber disposed between said pistons.

The device may further include a lubricating and/or cooling systemcomprising a delivery channel in the connecting shaft and the secondcoupling means for delivering lubricant and/or coolant from externallyof the converter to the first member so that the orbital movement of theconnecting shaft assists in distributing the fluid at selected positionsat or around the first member. The fluid may be circulated by a pumpingaction or centrifugal force.

Further features of the present invention will be apparent from thefollowing description of preferred embodiments as illustrated in theaccompanying drawings.

In the drawings:

FIG. 1 is a longitudinal section through a first embodiment of a motorconstructed in accordance with the present invention (taken along lineI--I of FIG. 2);

FIG. 2 is a cross-sectional view along the line II--II of FIG. 1;

FIG. 3 is a longitudinal section through a second embodiment of a motorwhich is constructed in accordance with this invention;

FIG. 4 is a cut-away perspective view of a unit of the presentinvention;

FIG. 5 is a perspective sketch of a single piston, an associated shaft,and their interconnections, partly cut-away at the central, longitudinalsection thereof, this sketch being partly schematic; and

FIG. 6 illustrates (in a partly sectional, partly schematic drawing) theuse of two links between a sleeve on the connecting shaft connected to apiston and respective mounting points for the links on the engine orpump housing.

Means (not shown) such as openings in the cylinder which may be providedwith suitable valving arrangements may be provided to communicate witheach of the working chambers 18 and 19 for admission of working fluid toeach chamber and subsequent removal of working fluid therefrom. Theworking fluid may either be a fluid under pressure, (for example, apressurised gas such as air or steam or a pressurised liquid such ashydraulic oil) or a fluid which expands on ignition. In the latter case,each working chamber may also be provided with a suitable ignitiondevice of any known type.

Shaft 20 extends eccentrically of the cylinder 12 and is eccentricallymounted at each end on the inner faces of disc members 21 and 22.Mounted concentrically on the outer faces of disc members 21 and 22 areoutput shafts 23 and 24, shafts 23 and 24 being mounted for rotation bysuitable bearing means in end walls 25 and 26, respectively, of thecylinder 12.

Each of the pistons 14, 15 16, 17 is coupled to shaft 20 such that axialreciprocation of the pistons causes orbital movement of the shaft withincylinder 12. As depicted in FIGS. 1 and 2, this coupling comprisessleeves 27, 28 and 29 surrounding shaft 20 and axially reciprocablethereon. It will be noted that whilst pistons 14 and 17 are mounted atone end of each of sleeve 27 and 29 respectively, pistons 15 and 16 aremounted one at each end of single sleeve 28 for movement in unison ofthese pistons. Thus, expansion of a working fluid within working chamber18 will move piston 14 and sleeve 27 to the right, and piston 15 andsleeve 28 to the left, from the positions as shown in FIG. 1. Thismovement can be utilized to exhaust spent working fluid from chamber 19by movement of piston 16 also to the left and movement of piston 17 andsleeve 29 to the right, in addition to rotation of the discs 21 and 22on orbital movement of shaft 20 and hence rotation of output shafts 23and 24 as will now be described.

Discs 21 and 22 are caused to rotate by axial movement of sleeves 27, 28and 29 along shaft 20 by means of reciprocating link arms 27A, 28A and29A which extend through longitudinal slots 30, 31 and 32, respectivelyin the cylinder 12. Each of the link arms is pivotally mounted at oneend thereof to a respective one of the sleeves 27, 28 and 29, and at theother end thereof at a fixed point externally of the cylinder 12 withina longitudinally extending housing 33. (If desired, the embodimentillustrated may be modified so that this fixed point is internally ofthe cylinder 12). As will be apparent from FIG. 2, each link arm 27A,28A and 29A is mounted within housing 33 to not only reciprocate axiallyof the cylinder but also is pivotal in the transverse direction thereto.It will be appreciated that because of the link arms, as each sleeve isforced axially of the shaft 20, the shaft will be forced to perform anorbital movement, for example in the direction of arrow A in FIG. 2,hence the discs 21 and 22 and output shafts 23 and 24 will be rotated.

If desired, the pivot point for each of the link arms 27A, 28A and 29Acan be varied within the housing 33 or cylinder 12. This will have theeffect of varying the compression within working chambers by alteringthe top and bottom dead center positions of the pistons. In addition,variation of the length of these link arms will enable the length of the"stroke" to be selected as desired.

Turning now to FIG. 3, the fluid operated motor illustrated is in manyrespects similar to the motor illustrated in FIGS. 1 and 2. Thus, itcomprises a cylinder 112, pistons 114, 115, 116 and 117 movable axiallytherein and defining working chambers 118 and 119. In this embodiment,however, four shafts 120, 121, 122 and 123 are provided eccentrically ofthe cylinder 112, and sleeves 124, 125, 126 and 127 are axiallyreciprocable on respective ones of these shafts, each of these sleeveshaving a respective one of the pistons 114, 115, 116 and 117 mountedthereon. It will be appreciated that the respective pistons and sleevecould be one piece. Link arms 128, 129, 130 and 131 extend pivotallybetween a respective sleeve and an external pivot point as described andshown in detail in FIGS. 1 and 2. It will be seen in FIG. 3, however,that shafts 120, 121, 122 and 123 are mounted eccentrically on one faceof a respective toothed disc 132, 133, 134 and 135, each of which ismounted for rotation within the cylinder 112. Discs 132, 133, 134 and135 each mesh, through an appropriate aperture in the wall of cylinder112 with external gears 136 mounted on external output shaft 137. Thus,orbital movement of shafts 120, 121, 122 and 123 caused by axialmovement of pistons 114, 115, 116 and 117 and sleeves 124, 125, 126 and127 on expansion or contraction of working chambers 118 and 119, andlink arms 128, 129, 130 and 131 is transmitted as rotary motion to theoutput shaft 137

If desired, an external output shaft equivalent to output shaft 137 ofFIG. 3 may be incorporated into the embodiment of FIGS. 1 and 2, such ashaft being mounted for example on the side of the cylinder 12 oppositeto the housing 33. Similarly, a single through-shaft equivalent to shaft20 of FIG. 1 may, if desired, be incorporated into the embodiment ofFIG. 3 in place of the half shafts 120, 121, 122 and 123.

Referring to FIG. 4 there is shown an arrangement comprising a cylinder112, two pistons 114 and 115 disposed therein with a working chambertherebetween. The interconnection between the pistons 114 and 115 to theoutput shaft 137 is the same and, as such, only the parts for piston 114have been itemized. The piston 114 is operatively connected to aneccentric sleeve 124 which is reciprocable on connecting shaft 120 whichin turn is connected to disc-like member 132. A link member 128 extendsbetween the sleeve 124 and a mounting point which is fixed but enableslimited universal movement of the link member 128 relative thereto. Thedisc member 132 has an external gear section which is connected to gearwheel 138 which in turn is operatively connected to shaft 137.

The operation of the device shown in FIG. 4 is the same in principle tothat described earlier. Working fluid is adapted to enter and bedischarged from the working chamber between the pistons so that powercan be transmitted to output shaft 137.

Referring to FIG. 5, there is shown a cylinder 12 with a piston 14moveable axially therein. The face or crown 14A of piston 14, with theface or crown 15A of second piston 15 mounted within cylinder 12, andwith the inner wall of cylinder 12, defines a working chamber 19 incylinder 12. This arrangement is essentially the same as that shown inFIG. 4. Other components of the portion of the engine depicted in FIG. 5all having corresponding features described earlier in the specification(and thus requiring no further explanation) are shaft 20 which iseccentric of cylinder 12, sleeve 29, disc 21, output shaft 24, housing33, link arm or link 27, slot 30 in cylinder 12, and pivotal mountingarrangement 34 which includes a shaft 35 connected to housing 33. Theoperation of an engine or pump having these features will be apparentfrom the earlier description.

As shown, there is provided in shaft 24, disc 21 and shaft 20 of atleast one channel (a single channel 40 is shown in FIG. 5) through whicha fluid can pass, to enter the region in cylinder 12 which is locatedbetween the back of piston 14 and the disc 21, and/or to enter otherparts of the engine. To permit the fluid to enter the region betweenpiston 14 and the disc 21, at least one aperture 41 will be provided inshaft 20 and its surrounding sleeve 29, to provide a passage to enablethe fluid to leave the channel 40.

The fluid which flows through channel 40 will normally be a lubricant(such as oil), a coolant or a gas which also cools the pistons of theengine.

If the fluid is oil, it will normally enter the sump of the engine, inthe bottom of housing 33, through the slot 30. If the fluid is a gas, itwill also leave the inside of cylinder 12 through slot 30, to be ventedto atmosphere through an aperture or valve in housing 33. If theinterior of the housing 33 is to be maintained at a pressure which isgreater than atmospheric pressure, the venting to atmosphere will bethrough a valve.

If the fluid is to be used only to cool the pistons, aperture 41 will beomitted and the fluid will be supplied, via orifice 42 which connectswith channel 40, to the hollow interior region 14B of piston 14. Thecoolant fluid will then leave region 14B via (a) a second channelrunning parallel to channel 40, (b) at least one aperture 43 in the rearof piston 14, or (c) at least one aperture (not shown in the drawing)which is located in the side wall of piston 14, rearward of thecompression piston rings. It will be appreciated that in someapplications no piston rings would be necessary. If this coolant is, orcontains, oil which is also used for lubrication, it may leave theregion 14B via at least one aperture located in the side wall of piston14 rearward of the compression piston rings but forward of the scraperor oiler ring (if present). Aperture 43 may be provided with a valve tocontrol the flow of coolant through the aperture. In anotherarrangement, the aperture may be omitted thereby providing a cushioningeffect on the stroke.

The fluid may be pumped through channel 40, or it may be circulatedthrough channel 40 by the combination of one-way valves and thereciprocal movement of the piston 14, or it may be circulated solely bythe reciprocal movement of the piston 14. The same arrangements may beadopted if the fluid has to flow through more than one channel, or inone direction through one channel and in the reverse direction throughanother channel. If one-way valves are used, they may be positioned inany suitable location in the flow path of the fluid.

Referring to FIG. 6 there is shown a modification which comprises theuse of a plurality of links or link arms 50 connected to each sleeve 29.It should be noted that sleeve 29 is normally attached to shaft 20 insuch a manner that there is no rotational movement between shaft 20 andsleeve 29. Thus it is not essential that shaft 20 has a circularcross-section. The circumference of a section through the shaft 20 maybe circular but with one or more chords replacing part of the circle, orit may be elliptical, or hexagonal, or the shape of any other polygon,or (in general terms) any continuous or interrupted conic section.Desirably, the bearing surface 23 on which the connection to one end oflink moves, has a circular cross-section using a shaft 20 having anon-circular cross-section, one end of which is seated in a small wellin the back of piston 14, prevents the tendency of the side of thepiston 14 to touch the inner wall of cylinder 12 during rotation of thepiston.

The ends of link arms 50 which are remote from sleeve 29 are connectedto respective pivotal mounting points connected to rods 55 mounted on tothe housing 33 of the engine.

An alternative arrangement (not shown in the drawings) is to provide amount to receive each rod 55, respectively, by affixing a bracket (or aplurality of brackets) to the exterior of the cylinder 12, with the (oreach) bracket having at least one bearing point adapted to receive anend of a rod 55.

The use off two or more links 55 improves the smoothness of operation ofthe engine.

Another feature that may be incorporated into engines and pumps of thetype discussed above is the mounting of the shafts 20 and 20A (seeFIG. 1) of an opposed pair of pistons 14, 15 so that the axes of shafts20 and 20A are not substantially co-linear. Preferably, the shafts 20and 20A are mounted so that their axes lie on different radial planespassing through the axis of cylinder 12. More preferably shafts 20 and20A are mounted so that their axle lie on radial planes of cylinder 12which are 180° apart (that is, they lie on a diametral plane of cylinder12).

Yet another feature that may be incorporated into engines or pumps ofthis type is the shaping of the crowns or faces of the opposed pistonsin such a manner as to achieve maximum turbulence or swirl of thecombustion gases (or combustion aerosols or other type of combustionfluid) in the case of an engine, or of the gases, liquid or slurry inthe case of a pump.

I claim:
 1. A rotary/linear converter comprising:a first member having acentral axis and being adapted for linear movement in the direction ofsaid central axis; a second member adapted for rotational movement;connecting means operatively interconnecting said first and secondmembers so that respective linear or rotational movement of one saidmember causes respective linear or rotational movement of the other saidmember; characterized in that said connecting means comprises: aconnecting shaft disposed eccentrically of said central axis of saidfirst member; first coupling means operatively connecting said firstmember to said connecting shaft such that axial reciprocation of saidfirst member causes orbital movement of said connecting shaft and viceversa; and second coupling means operatively connecting said connectingshaft to said second member so that said orbital movement of saidconnecting shaft causes rotation of said second member and vice versa,wherein said first coupling means comprises a sleeve operativelyconnected to said first member for axial reciprocation therewith, saidsleeve being associated with said connecting shaft for axialreciprocation relative thereto and at least one link member extendingbetween said sleeve and a mounting which is in a fixed position.
 2. Arotary/linear convertor according to claim 3 further including a guidewithin or along which said first member is moved.
 3. A rotary/linearconvertor according to claim 2, wherein said first coupling meanscomprises a plurality of link members extending between said sleeve andrespective mountings which are fixed.
 4. A rotary/linear converteraccording to claim 2, wherein each said link members is pivotallyconnected to said sleeve and to said mounting for limited universalmovement.
 5. A rotary/linear convertor according to claim 2 wherein saidfirst member comprises a piston and said guide comprises a cylinderhaving a working chamber therein, inlet means and outlet meanscommunicating with said working chamber for the admission and removal ofsaid working fluid therefrom.
 6. A rotary/linear converter according toclaim 5 wherein said first member comprises two pistons disposed withinsaid cylinder there being a single working chamber disposed between saidpistons.
 7. A rotary/linear convertor according to claim 1 furtherincluding a lubricating and/or cooling system comprising a deliverychannel in said connecting shaft and said second coupling means fordelivering lubricant and/or coolant from externally of the convertor tosaid first member so that the orbital movement of said connecting shaftassists in distributing the fluid at selected positions at or aroundsaid first member.
 8. A rotary/linear converter comprising:a firstmember having a central axis and being adapted for linear movement inthe direction of said central axis; a second member adapted forrotational movement; connecting means operatively interconnecting saidfirst and second members so that respective linear or rotationalmovement of one said member causes respective linear or rotationalmovement of the other said member; characterized in that said connectingmeans comprises: a connecting shaft disposed eccentrically of saidcentral axis of said first member; first coupling means operativelyconnecting said first member to said connecting shaft such that axialreciprocation of said first member causes orbital movement of saidconnecting shaft and vice versa; and second coupling means operativelyconnecting said connecting shaft to said second member so that saidorbital movement of said connecting shaft causes rotation of aid secondmember and vice versa, wherein said second coupling means comprising adisc-like member mounted for rotation about an axis, said connectingshaft being eccentrically connected with respect to said axis to saiddisc-like member, said second member being operatively connected to saiddisc-like member.
 9. A rotary/linear convertor according to claim 8wherein said second member is operatively connected to said disc-likemember co-axially therewith.
 10. A rotary/linear converter according toclaim 8 wherein said second member is radially displaced from the axisof said disc-like member and operatively connected thereto bytransmission means.
 11. A rotary/linear convertor according to claim 10wherein said disc-like member comprises a circumferential gear sectionadapted to engage a further gear which is operatively connected to saidsecond member.